Auxiliary wave propagating and directing attachment for loudspeaker diaphragms



y 29, 1958 A. B. COHEN ETAL 2,845,135

AUXILIARY WAVE PROPAGATING AND DIRECTING ATTACHMENT FOR LOUDSPEAKERDIAPHRAGMS Filed Sept. 26, 1955 4 Sheets-Sheet 1 1N VENTORS ATTORNEYJuly 29, 1958 A. B. COHEN ETAL AUXILIARY WAVE PROPAGATING AND DIRECTINGATTACHMENT '-.FOR LOUDSPEAKER DIAPHRAGMS 4 Sheets-Sheet 2 Filed Sept.26, 1955 INVENTORS X M ATTORNEYS.

y 29, 1958 A. B. COHEN ETAL 2,845,135

AUXILIARY WAVE PROPAGATING AND omsc'rmc ATTACHMENT '"FOR LOUDSPEAKERDIAPHRAGMS 1 Filed Sept. 26, 1955 4 Sheets-Sheet 3 INVENTORS. 4-6- X I IATTORNEYS y 9, 1958 A. B. COHEN ET AL 2,845,135

AUXILIARY WAVE PROPAGATING AND DIRECTING ATTACHMENT FOR LOUDSPEAKERDIAPHRAGMS 4 Sheets-Sheet 4 Filed Sept. 26, 1955 INVENTORS.

ATTORNEYS United States Patent i AUXILIARY WAVE PROPAGATING AND DIRECT-lNG ATTACHMENT FOR LOUDSPEAKER DIA- PHRAGMS Abraham B. Cohen, Bronx, andSidney E. Levy, White Plains, N. Y.; said Cohen assignor, by mesneassignments, to Arthur Blumenfeld, New York, N. Y.

Application September 26, 1955, Serial No. 536,624

5 Claims. (Cl. 181-31) The present invention relates to attachments forloud-- speaker diaphragms, and more particularly to a novel attachmentwhich is adapted to be associated with a loudspeaker diaphragm in such amanner and which is so constructed as to improve the mid-frequency andhigh frequency response of a loudspeaker embodying the invention.

Heretofore, loudspeaker diaphragms have been provided with supplementalor auxiliary sound diffusing attachments adapted to increase the spreador dispersion of the mid-frequency or high frequency sound wavesgenerated by the diaphragm, wherein the attachments were in the form oftransversely arched stiifeners of circular form. Such stiffeners weregenerally provided with apertures therethrough, whereby sound generatedbehind the stiffeners was diffused at the apertures and dispersed in alldirections or concentrated and directed towards the axis of the path ofsound travel.

In other previous types of loudspeakers, specially designed horns havebeen developed for producing more uniform dispersion of sound over thehorizontally extended area in front of the speaker, while limitingvertical spread or dispersion of the sound waves.

The present invention contemplates as its primary objective combining ina sound reproducing structure the desirable characteristics of adiffuser and a special horn, both as above referred to, whereby themid-frequency and high frequency response of a loudspeaker is improved.

Another object is to provide a conventional conical loudspeakerdiaphragm with an auxiliary or supplementary sound propagating ordiffusing attachment which is so constructed as to direct middle or highfrequency sound waves generated adjacent to the apex or center of thediaphragm, or by the attachment itself, axially, while maintaining at aminimum sound radiation or dispersion in vertical directions, thusconserving signal energy which is utilized to expand horizontal soundradiation or dispersion.

The foregoing objective may be obtained by the utilization of asupplementary horn-like attachment which is so formed as to be capableof being attached to a conventional conical diaphragm adjacent to itscenter axis or adjacent to the usual voice coil bobbin with which suchloudspeaker diaphragms are usually provided, and which is formed withside walls which flare laterally or horizontally to a larger extent thanthe top and bottom walls do vertically, and so that a substantiallyrectangular mouth is provided.

As will hereinafter appear, the supplementary horn-like attachment maybe of a number of diflerent forms, and instead of having a rectangularmouth defined by lateral or vertical walls which are farther spacedapart than the top and bottom horizontal walls, the mouth may be square.

In addition, the flare or expansion of the horn-like attachment may beproduced in various manners, as by the provision of relatively straightdiverging walls, longi 'ice of divergence. In the latter case, thecompound angle of divergence or expansion of the opposed walls of theattachment is preferably such that dispersion of sound Waves ispredominantly in a vertical direction initially, but subsequentlydispersion of the sound waves is predominantly in a horizontaldirection, and during the subsequent stage of dispersion, the opposedtop and bottom walls, in restricting vertical dispersion, build uppressure which increases the signal energy or amplitude in a horizontaldirection.

A further object is to provide a sound reproducing assembly comprising apair of coaxially arranged sound propagating elements adapted to beactuated or vibrated by a common voice coil to produce sound waves, oneof said elements being so constructed as to generate midor highfrequency sounds and being so configurated as to etfect dispersion ofsounds generated thereby over a wide angle in one plane, whilerestricting such sound waves to limit the dispersion in a plane normalto the first-mentioned plane.

Other objects and advantages will be hereinafter described or willbecome apparent to those skilled in the art, and the novel features ofthe invention will be defined in the appended claims.

In the drawings:

Fig. 1 is a view in perspective, showing a loudspeaker diaphragm withone form of horn-like attachment mounted in assembled relation to thediaphragm in accordance with our invention;

Fig. 2 is a fragmentary plan view, showing another horn-like attachmentsomewhat similar to that of Fig. I mounted in assembled relation with aloudspeaker diaphragm;

Fig. 3 is a view in section, as taken on the line 33 of Fig. 2;

Fig. 4 is a view in section, as taken on the line 44 of Fig. 2;

Fig. 5 is a plan view of a modified form of horn-like attachment;

Fig. 6 is a view in section, as taken on the line 66 of Fig. 5;

Fig. 7 is a view in section, as taken on the line 77 of Fig. 5; and

Fig. 8 is a view in perspective, showing a further modified form ofhorn-like attachment mounted in assembled relation with a loudspeakerdiaphragm.

Referring first to Figs. 1 through 4, 1 denotes a conventional cone-typeloudspeaker diaphragm having an enlarged mouth bordered by a compliantcorrugated marginal flange 2 adapted to be mounted on a suitable support(not shown). The diaphragm 1 tapers towards its end remote from theflange 2 and is provided with a central opening in which is adapted tobe disposed the usual cylindrical voice coil support or bobbin 3 onwhich is disposed a voice coil winding 4. Bridging the end of the voicecoil bobbin 3 in a conventional manner to provide a dust cap or closureto preclude the passage of dust or the like through the bobbin into thearea behind the diaphragm, is a domed closure 5 which is preferablyformed integrally on the bobbin 3.

All of the parts above described are conventional, and ordinarily theapex or small end of the diaphragm 1 would be attached, as by cementing,to the outer periphery of the bobbin 3, and therefore, the diaphragm isshown as having thereon a short axially extended flange 6 at its apexend which would enable attachment of the dia phragm 1 to the voice coilbobbin 3. However, in the illustrative embodiment of the presentinvention, an attachment tab or flange 7 of a horn-like attachmentgenerally designated 8 is interposed between the bobbin 3 and diaphragmflange 6, and these elements are prefera- 3 bly secured together in anassembly as by cementing or the like.

The attachment 8, as seen in Figs. 1 through 4, has a pair of opposedlongitudinally extended straight lateral walls 9, 9 which diverge awayfrom the flange 7 and are generally arcuate in cross section. At theouter or forward end of the walls 9, they are each turned radiallyoutwardly to form a flange 10, each flange 10 being corrugated so as toform a compliant section 11. Outwardly of the compliant sections 11,each flange 10 preferably has a section 12 projecting towards thediaphragm 1 and having a terminal tab 13 for attachment as by cementingto the diaphragm.

Intereonnecting the lateral walls 9 of the horn-like attachment 8, is apair of opposed top and bottom walls 14, 14, each of which istransversely arched where it merges with the flange 7, these walls 14diverging away from the flange 7, with the arch in each wall 14progressively enlarging until the wall becomes flat at its forwardextremity and terminates in planar relation with the lateral walls 9.The forward extremity of each wall 14 is preferably turned outwardly andback upon itself to form a reinforcingbead 15 which preferably mergesand blends with the initial corrugation of compliant sections 11 oflateral walls 9.

Accordingly, it will be seen that the attachment has at its so-calledrear end a circular central opening 16 defined by the flange or tab 7,and the opposed walls 9 and 14 diverge away from the opening 16 to formthe hornlike member. Preferably, the angle of divergence of the lateralwalls 9 is larger than the angle of divergence of the opposed top andbottom walls, so that a generally rectangular mouth is provided, saidmouth having a greater lateral extent than its vertical extent, as bestseen in Figs. 1 and 2.

In addition, the angular relation of the walls 9 and 14 is such that theprogressive internal expansion or flare of the horn-like attachment 8 isin accordance with one of the conventional exponential rates which maybe readily determined by the use of any well-known formula fordetermining the flare or expansion factor of loudspeaker horns.

As illustrated in Fig. 1, the flange 10 on each lateral wall 9 of theattachment 8 is preferably provided with a plurality of longitudinallyextended openings 17 disposed in side-by-side laterally spaced relation.Therefore, in operation of the sound reproducing assembly, sound wavesgenerated by diaphragm 1 behind the flanges 10 will not be trapped orreflected, but will pass through the respective openings 17 and bedispersed in wavelets emanating from each opening.

Moreover, the form of the horn-like attachment 8 will cause midand highfrequency sound waves generated thereby or at the rear end of theassembly to be directed primarily in a wide horizontal area in front ofthe assembly, while limiting vertical spread or dispersion of suchmidand high frequency sounds. While in this specific illustrativeembodiment, the horn-like attachment 8 is shown as secured to the outerperiphery of the voice coil bobbin 3, it should be understood that therear end of the attachment 8 may be secured at other points withoutdeparting from the invention, as on the domed cap of the bobbin 3 or onthe body of diaphragm 1 at a position forwardly spaced from the bobbin3.

Referring to Figs. 5, 6 and 7, there is shown a slightly modiliedform ofhorn-like attachment generally designated 8'. In this modified form, thebody of the attachment, instead of having relatively straight divergentwalls, is formed so as to be arched longitudinally,thus flaring on acurve. While at the small or rear end 7', the horn-like attachment 8' isannular in cross section, vertical expansion of the attachment 8' isprogressively less than lateral expansion of the attachment as thecontinuous walls of the body thereof approach the forward end of theattachment, and therefore, the cross-sectional form of the horn changesfrom an annular or circular form through a progressively lengtheningelliptical form, until the forward extremity of the attachment isreached. Preferably, at its forward extremity, the horn-like attachment8 has its upper and lower margins straight and provided with areinforcing bead 15', while the lateral sides of the attachment 8 arearcuate in cross section at the forward extremity and are provided withcompliant attaching flanges 10' as previously described in connectionwith Figs. 1 through 4.

Where applicable, primed reference numerals corresponding to those usedin Figs. 1 through 4 are applied to Figs. 5, 6 and 7 to designatecorresponding or equivalent parts, and therefore, the remaining detailsof th horn-like attachment 8 need not be further described.

It should be understood, that the horn-like attachment 8', if desired,may also be provided with a plurality of longitudinally extendedopenings such as those designated 17 in Fig. 1.

Referring now to Fig. 8, there is illustrated a further modifiedhorn-like attachment generally designated 8" which is adapted to beconnected with a diaphragm 1" in the same manner as has been previouslydescribed. The illustrative attachment 8" is shown as having opposedside wall-s 9", 9" and opposed top and bottom walls 14', 14", butinstead of having attaching flanges only atthe lateral ends of therectangular mouth of the attachment 8", the mouth is provided with acompliant flange portion 11" extending about the entire forwardextremity of the attachment 8", and a portion 12" extending from thecompliant portion 11" towards the diaphragm 1" completely about theattachment 8", the latter portion having a marginal edge 13 adapted tobe cemented to the diaphragm 1". In addition, the flange portion 12 ispreferably provided with spaced openings 17" disposed in side by siderelation about the entire flange, as is clearly illustrated.

The body of attachment 8", in lieu of the form shown in Fig. 8, mayalternately have the form of Figs. 5, 6 and 7, as should be apparent.

The respective horn-like attachments herein disclosed are preferablyfabricated of paper of a fibrous character capable of being molded, butthese attachments maybe made of other materials without departing fromthe spirit of the invention, such as thin plastic, aluminum, or othersuitable materials which are light in weight and have suffioientrigidity to maintain their form without distortion under vibration. A

Other changes and alterations may be made without departing from thespirit of the invention as defined in the appended claims.

We claim:

1. In a sound reproducing device including a vibratory diaphragm and alongitudinally extendal shorn-like attachment mounted coaxially withrelation to said-diaphragm and connected thereto for vibrationtherewith,

said attachment having a small end and a large end'and progressivelyexpanding in cross-sectional area from the small end to the large end,that improvement wherein the horn-like attachment expands in one planeat a greater angle than in a plane normal to the first-mentioned plane,and said horn-like attachment having a flange at its large endprojecting into engagement with said diaphragm and secured to saiddiaphragm, said flange having a compliant section interposed between thediaphragm and themain body of the attachment.

2. In a sound reproducing device including a vibratory diaphragm and alongitudinally extended horn-like attachment mounted coaxially withrelation to said diaphragm and connected thereto for vibrationtherewith, said attachment having a small end and a large end andprogressively expanding in cross-sectional area from the small end tothe large end, that improvement wherein the horn-like attachment expandsin one plane at a greater angle than in a plane normal to thefirst-mentioned plane, and said horn-like attachment having a flange atits large end projecting into engagement with said diaphragm and securedto said diaphragm, said flange having a plurality of sound diffusingopenings therein for liberating and diffusing sound waves generated bysaid diaphragm behind said flange.

3. In a sound reproducing device including a vibratory diaphragm and alongitudinally extended horn-like attachment mounted coaxially withrelation to said diaphragm and connected thereto for vibrationtherewith, said attachment having a small end and a large end andprogressively expanding in cross-sectional area from the small end tothe large end, that improvement wherein the horn-like attachment expandsin one plane at a greater angle than in a plane normal to thefirst-mentioned plane, and said hornlike attachment having a flange atits large end projecting into engagement with said diaphragm and securedto said diaphragm, said flange having a plurality of sound diffusingopenings therein for liberating and diffusing sound waves generated bysaid diaphragm behind said flange, and said flange extending completelyabout the periphery of the large end of said horn-like attachment.

4. An attachment for vibratory loudspeaker diaphragm assemblies,comprising a longitudinally extended hornlike member having one endadapted to be connected to the diaphragm assembly for vibrationtherewith, said member expanding in cross-sectional area towards itsopposite end and having a generally rectangular mouth, and said memberhaving a laterally projecting flange adjacent its mouth and adapted tobe secured to the diaphragm aforesaid, said flange having a compliantportion adjacent to the point of attachment of the flange to thediaphragm,

5. An attachment for vibratory loudspeaker diaphragm assemblies,comprising a longitudinally extended hornlike member having one endadapted to be connected to the diaphragm assembly for vibrationtherewith, said member expanding in cross-sectional area toward itsopposite end and having a generally rectangular mouth, and said memberhaving a laterally projecting flange adjacent its mouth and adapted tobe secured to the diaphragm aforesaid, said flange having a plurality ofsound difiusing openings therethrough.

References Cited in the file of this patent UNITED STATES PATENTS1,984,542 Olson Dec. 18, 1934 2,565,069 Engholm Aug. 21, 1951 2,568,883Carrington Sept. 25, 1951 2,641,329 Levy et a1. June 9, 1953 2,685,935Lenz Aug. 10, 1954

